Dresser for abrasive wheels

ABSTRACT

A dresser including a nest of cutter discs having teeth arranged about their periphery, central openings for loosely receiving a supporting shaft and partially interfitting projections and recesses arranged in an annular area thereof in close proximity to the roots of the teeth. End washers are employed to exert pressure on the discs in a direction axially of the supporting shaft in an annular area thereof intermediate the central openings and the projections and recesses, whereby to resiliently deform certain of the discs in order to impart rigidity to the nest of discs both radially and annularly thereof.

Wise

[76] Inventor: Kenneth J. Wise, 167 Glencove Rd.,'

Kenmore, NY. 14223 [57] ABSTRACT 22 F1 d: F b. 5 1973 1 16 e A dresser including a nest of cutter dlSCS having teeth PP NOJ 329,758 arranged about their periphery, central openings for loosely receiving a supporting shaft and partially inter- 52 us. Cl. .Q 125/37 fitting Projections and arranged in an annular 51 Int. Cl B24b 53/14 area thereof close Proxnmty the roots of the [58] Field of Search 125/11 CD, 37 teeth; f hers are employed to exert pressure on v the dlscs in a direction axially of the supporting shaft [56] References Cited in an annulgrharea thereof intgrmediate thg ceitral UNITED STATES PATENTS openings an t e pro ections an recesses, w ere y to resiliently deform certain of the discs in order to 1m- 990,l93 4/1911 Br sben 125/37 part rigidity to the nest of discs both radially and 1,425,94l 8/1922 Brlsben 125/37 nularl thereof 2,742,891 4/1956 Wise 125/37 y 3 Claims, 6 Drawing Figures age 35 34 W s 3 4 $1 30 25 32 s -H IHI WW-TH, \l\\ 42 I II I I 7 1% \7' "w L- q z gfigf J r 23 22 \2 I8 44 L v 3 15 l9 s I United States Patent [191 DRESSER FOR ABRASIVE WHEELS [451 Aug. 6, 1974 Primary Examiner-Harold D. Whitehead Attorney, Agent, or Firm-Bean 8L Bean I DRESSER FOR ABRASIVE WHEELS BACKGROUND OF THE INVENTION In my prior U.S. Pat. No. 2,742,891, there is disclosed a dresser for truing the surfaces of emery and other grinding wheels, which comprises a nest of toothed cutter discs slip fitted onto a non-round central portion of a supporting shaft; the shaft being in turn end journaled by bearings carried by a bifurcated dresser housing or body. The discs are formed with non-interfitting elevations and depressions, which are intended to space the discs axially of the supporting shaft and cooperate with a pair of end washers to deflect the discs sufficiently to place inner edges of their central openings in positive and binding engagement with the surface on the shaft.

SUMMARY OF THE INVENTION The present invention relates to dressers for abrasive wheels and more particularly to the improvements in the construction of the cutter discs and shaft supporting arrangement disclosed in U.S. Pat. No. 2,742,891.

In accordance with the present invention, cutter discs are formed with a plurality of partially inter-fitting projections and recesses, which are disposed within an annular region of the discs arranged in close proximity to the roots of the disc teeth. Further, the shaft receiving opening of each disc is oversized to prevent full inner edge to shaft surface engagement when the discs are deflected or deformed by the end washers; engagement between such inner edges and the shaft being limited to point contact at a number of points determined by the number of side surfaces defined by the shaft and the disc opening. This construction results in annular as well as radially directed tensioning of the discs arranged adjacent opposite ends of the nest of discs in order to provide for an extremely rigid dresser construction, and to minimize transmission of vibration from the discs to the shaft and thus the dresser housing. Additionally, fabrication is facilitated, since extremely accurate shaft and disc opening tolerances need not be maintained.

The dresser of the present invention additionally features a simplified shaft mounting arrangement, which permits the dresser housing shaft bearing receiving openings to be accurately formed by a single through boring operation.

DRAWINGS The nature and mode of the present invention will now be more fully described in the following detailed description taken with the accompanying drawings wherein:

FIG. 1 is an axial sectional view taken through wheel dresser of the present invention;

FIG. 2 is a sectional view taken generally along line 22 in FIG. 1;

FIGS. 3 and 4 are fragmentary views of similar surface portions of adjacent discs showing a preferred arrangement for staggering the teeth of such discs;

FIG. 5 is an enlarged fragmentary view of the area designated as FIG. 5 in FIG. 1; and

FIG. 6 is an end view of the present wheel dresser, but with the dresser discs removed.

DETAILED DESCRIPTION The dresser of the present invention is generally designated at 10 in FIG. 1 and shown as including a bifurcated dresser housing or body portion l2 having spaced first and second arm portions 14 and 15. Dresser housing 12 may be either held in the hands of an operator or rigidly clamped to a suitable traversing structure in order to accurately control presentation of the dresser to an abrasive wheel.

In accordance with the preferred form of the present invention arm portions 14 and 15 are formed with axially aligned, through bored, identically sized apertures 16 and 17, which are of circular cross-sectional configuration. For the purpose to be hereinafter described, first arm portion 12 may be considered as being formed with first and second stop surfaces 18 and 19, which are arranged to extend radially from adjacent opposite ends of aperture 16.

Closely fitted within apertures 16 and 17 are the outer races 20 and 21 of a pair of anti-friction bearings whose inner races 22 and 23 are in turn closely fitted over cylindrical portions 24 and 25 of a shaft 26 for abutting engagement with a pair of cylindrical portion slide fitted collars or washers 28 and 29. Shaft cylindrical portions 24 and 25 are arranged intermediate a central, relatively enlarged, non-round portion 30 and threaded end portions 32 and 33, which freely receive washers 34 and 35 and threadably receive end nuts 36 and 37. Preferably, portion 30 is of a polygonal crosssectional configuration, such as a square. One or both of collars 28 and 29 may be dished to define a centrally disposed cavity or recess 38, which is bounded by an annular pressure transmitting rim 40, but in any case each abut against the opposite ends of portion 30, as shown in FIG. 1.

As will be apparent, when end nuts 36 and 37 are threaded onto end portions 32 and 33, inner races 22 and 23 are clamped between washer 34 and collar 28 and between washer 35 and collar 29, respectively, thereby to positionally orient the bearing devices axially of shaft 26. This assembly is in turn positionally oriented relative to dresser housing 12 by constraining devices in the'form of first and second threaded fastener devices 42 and 44, which are threadably received within openings 42a and 44a, which pass through stop surfaces 18 and 19, respectively. The axes of openings 42a and 44a are spaced radially from aperture 16 through a distance less than about one-half the diameter of the heads of fasteners 42 and 44, thereby to permit the latter to clampingly engage opposite ends of outer race 20. Of course, outer race 20 would have an axial length corresponding to or slightly in excess of the distance between stop surfaces 18 and 19 in order to permit the outer race to be clampingly engaged by the headed fasteners. Preferably, as shown in FIG. 6, the headed fasteners would be employed in pairs arranged in an annularly spaced relationship.

With the construction thus far described, apertures 16 and 17 may be formed by a single straight through boring operation, which insures perfect alignment of the apertures and resultant long operating life of the anti-friction bearing devices. Moreover, fabricating costs are reduced as compared to the two-step boring operation required to form apertures of the dresser of my prior U.S. Pat. No. 2,742,891.

Referring particularly to FIGS. 1 and 2, it will be seen that a plurality or nest of resiliently deformable, metal cutter discs 50 are mounted on central shaft portion 30 and for this purpose are formed with complimentary shaped central openings or holes 52. Each of the cutter discs may be cut from sheet material and deformed by one or more punch and die operations to provide central hole 52, peripheral cutter teeth 54 and a plurality of annular spaced relatively aligned projections and recesses 56 and 58; the latter being disposed in an annular area of the disc, which is arranged closely adjacent the roots of teeth 54.

The projections and recesses are of circular crosssectional configuration and relatively dimensioned in order to permit partial inter-fitting of the projections and recesses of adjacent discs, while maintaining desired spacing between the teeth of adjacent discs, as best shown in FIG. I. It will be noted that the disc engaging surfaces or rims 40 of the collars 28 and 29 are of smaller diameter than the annular area in which the projections and recesses are located. Accordingly, when end nuts 36 and 37 are tightened, certain of the discs adjacent opposite ends of the nest are caused to resiliently deform in op'posite directions to assume an outwardly concave or disc shaped configuration; the degree of disc deformation being progressively greater towards opposite ends of the nest, as indicated in an exaggerated manner by the phantom line showing in FIG. 5. Before tightening of the end nuts, each pair of associated projections and recesses of adjacent discs engage one another along annular line or band disposed concentrically of a line passing essentially centrally therethrough and parallel to the axis of shaft 26. As the end nuts are tightened, however, the associated projections and recesses tilt" relative to one another such that their line or band of contact becomes arcuate, as indicated by dash lined 60 in FIG. 2, and centers at the radially innermost point of their associated surfaces, as indicated as point 62 in both FIGS. 2 and 5. As a result, at least the end most discs of the nest, are tensioned r stressed in both radial and annular directions and the nest as a whole becomes extremely rigid. This is to be distinguished from prior constructions wherein the end most discs are merely deformed without cooperation between interfitted projections and recesses. In such prior constructions, outer annular portions of the end most discs are not constrained or pretensioned in the manner now contemplated with the result that the end most discs thereof have a tendency to flap, due to the extremely high nest speeds and loads involved during the dressing operation, and thus impart undesirable vibrations to the nest. It will be understood that the discs may be properly stressed without subjecting the end most discs to that degree of deformation, which will produce unacceptable displacements of their associated teeth relative to the teeth of the innermost discs. For a given nest and shaft sizing, the extent to which the discs will be deflected will be determined by the depth of disc recess 38.

By again referring to FIG. 2, as well as FIGS. 3 and 4, it will be seen that disc holes 52 are preferably sized to provide a loose fit on central shaft portion 30 in order to insure that their inner edge surfaces cannot be forced into full surface to surface or binding engagement with like surfaces of the shaft, when the discs are deformed in the manner described above. This arrangement, which is contrary to the teachings of my prior patent, insures only point contact between the discs and the shaft, that is four points of contact in the case of the illustrated squared shaft and hole arrangement, in order to minimize transfer of nest vibration to the holder via the shaft and bearing devices. Reduction in the transfer of vibration to the holder permits longer bearing life and facilitates mounting of the holder, whereas the use of a loose fit provides for disc and shaft fabricating economies. Normally, a disc hold side dimension exceeding the dimension of a like side of the shaft by an amount of between about 0.009 and 0.020 inches is sufficient for this purpose.

Reference is again made to FIGS. 3 and 4 for an illustration of a preferred construction providing for the maintenance of the accurately staggered tooth arrangement shown in FIGS. 1 and 2 without use of the shaft or additional disc fastener devices, such as for instance rivets, pins and the like. This is accomplished in accordance with the present invention by forming two sets of discs, which are identified by the letters X and O in FIGS. 3 and 4, respectively. The discs of these sets differ one from another only in the annular relationship of their teeth relative to a center line CL through a given reference projection 56 and side of hole 52. Thus, in the case of disc X the teeth are positioned such that the center line bisects a cutter tooth, whereas in disc 0" the center line bisects the root between a pair of adjacent teeth. When a nest of discs is assembled with alternately arranged disc types X and O, engagement of the projections and recesses of adjacent discs will serve to automatically align holes 52 of all the discs and to stagger the teeth of adjacent discs. The location of the teeth of the adjacent discs differ by one-half (1/2) the number of degrees between adjacent teeth. Thus, for example, with a 36 tooth design, there would be a 5 offset between the teeth of adjacent discs.

Any number of discs may be stacked together to make up a nest. To eliminate the necessity of a users handling, sorting and assembling discs X and 0, it is preferable for the supplier to pre-assemble nests of discs and temporarily retain same as an integral unit by passing one or more pieces of adhesive material about each of the nests. It will not be necessary for the user to thereafter remove the adhesive material in that it will quickly disintegrate upon use of the dresser.

I claim:

I. In a dresser for abrasive wheels having a housing, a nest of resiliently deformable cutter discs, a shaft journaled in at least one aperture in said housing for mounting said discs for rotation relative thereto, and clamping means on said shaft for clamping said discs together, said discs having peripherally arranged cutter teeth and centrally disposed polygonal holes, said shaft having a polygonal portion received within said holes whereby said discs and shaft turn together, the improvement comprising in combination:

each of said discs having a plurality of aligned projections and recesses formed on oppsite side surfaces thereof, said projections and recesses being arranged in an arcuately spaced relationship within an annular area of said side surfaces closely adjacent roots of said cutter teeth, said projections and recesses being relatively dimensioned to permit partial interfitting of projections and recesses of adjacent discs while maintaining facing side surfaces of said adjacent discs in a spaced relationship,

along an arcuate line of contact when tilted relative to one another as aforesaid.

3. An improvement according to claim 1, wherein said disc central holes are sized larger than said shaft portion whereby to prevent binding engagement between hole edge surfaces of said discs and surfaces of said shaft portion when said discs are deformed as aforesaid while permitting point contact of hole edge surfaces of said discs and surfaces of said shaft portion to permit said discs and shaft to turn together. 

1. In a dresser for abrasive wheels having a housing, a nest of resiliently deformable cutter discs, a shaft journaled in at least one aperture in said housing for mounting said discs for rotation relative thereto, and clamping means on said shaft for clamping said discs together, said discs having peripherally arranged cutter teeth and centrally disposed polygonal holes, said shaft having a polygonal portion received within said holes whereby said discs and shaft turn together, the improvement comprising in combination: each of said discs having a plurality of aligned projections and recesses formed on oppsite side surfaces thereof, said projections and recesses being arranged in an arcuately spaced relationship within an annular area of said side surfaces closely adjacent roots of said cutter teeth, said projections and recesses being relatively dimensioned to permit partial interfitting of projections and recesses of adjacent discs while maintaining facing side surfaces of said adjacent discs in a spaced relationship, said clamping means being engaged with side surfaces of endmost discs of said nest inwardly of said annular area with pressure sufficient to resiliently deform at least said endmost discs, said projections and recesses of said endmost discs being tilted relative to projections and recesses of adjacent discs with which they are partially inter-fitted and said endmost discs being stressed in both radial and annularly extending directions.
 2. An improvement according to claim 1, wherein said projections and recesses are of circular cross-sectional configuration therety to engage one another along an arcuate line of contact when tilted relative to one another as aforesaid.
 3. An improvement according to claim 1, wherein said disc central holes are sized larger than said shaft portion whereby to prevent binding engagement between hole edge surfaces of said discs and surfaces of said shaft portion when said discs are deformed as aforesaid while permitting point contact of hole edge surfaces of said discs and surfaces of said shaft portion to permit said discs and shaft to turn together. 